I have the same problem....the blower motor stays on high and the control knob the the fan makes no differents and when the head unit is shut off...the blower stays on high. I cleaned the tiny motor sensor behind the chrysler trim plate above the glove box. It gets full of lint. As, I was getting a code 34 but this still has not cleared up the problem. I even try replacing the atc resistor under the glove box on the firewall and this didn't do the trick either. Other, then the head unit being bad...I can't think of anything else. But, everything else works on the head unit and there seems to be no oter problem with it. Stumped!!!